Dec. 9, 2011 (San Antonio) -- A drug given to protect bones during breast cancer treatment extended the lives of young women with the disease, researchers report.
In a study of more than 1,800 premenopausal women, those given the bone-strengthening drug Zometa along with their cancer drugs were 37% less likely to die over a seven-year period than those who received standard therapy alone.
In 2008, the same researchers reported that women who got Zometa were less likely to have their cancer come back. At that point, the women had been followed for four years since starting treatment.
"Now, with seven years of follow-up, we see there is long-lasting benefit in term of both recurrences and survival," says researcher Michael Gnant, MD, of the Medical University of Vienna in Austria.
A total of 33 of 900 women given Zometa died vs. 49 of 903 women not given the drug.
Although some doctors say the research is too inconsistent at this point to declare Zometa an anti-cancer drug, Gnant tells WebMD the degree of benefit seen with Zometa is comparable to that of many chemotherapy drugs.
He presented the findings here at the San Antonio Breast Cancer Symposium. Gnant consults for Novartis, which makes Zometa and helped fund the study.
‘A New Standard of Care’
All had surgery to remove their tumors and were taking hormone-blocking drug treatments that made them menopausal. Half also were given infusions of Zometa once every six months for three years.
The most common side effects were bone and joint pain and fever. There were no cases of kidney failure or jawbone death, the major problems that have been linked to Zometa and other drugs in its class, called bisphosphonates.
Gnant says he will be offering Zometa to all of his premenopausal patients on hormone-blocking drugs.
"It’s a new standard of care [for such patients]," says James Ingle, MD, a breast cancer specialist at the Mayo Clinic in Rochester, Minn. Ingle was charged with putting the study's findings into perspective for doctors at the meeting.
A Mixed Bag
Animal and lab research suggests that bisphosphonates may fight breast cancer in a number of ways -- by directly killing tumor cells, by cutting off their blood supply, or by stimulating the immune system to mount an attack against the tumor.
Studies in women, though, have had mixed results. At last year's meeting, researchers reported that Zometa did not appear to prevent recurrences or cut deaths in most postmenopausal women, who account for three-fourths of all breast cancer cases.
Two other major studies also failed to show an overall benefit in terms of preventing cancer from coming back, says Harold Burstein, MD, PhD, of the Dana-Farber Cancer Institute in Boston.
And in another study presented at this year's meeting, the bisphosphonate pill Boniva failed to lower the risk of recurrence.
On the plus side, another new study showed postmenopausal women who received Zometa right away were 34% less likely to have a recurrence compared to those who were started on the bone drug at a later time.
All that makes Burstein hesitant to use Zometa or other bisphosphonates as cancer-fighting drugs.
"There are mixed reports in different patient populations with inconsistent benefits. At this point, there are insufficient data to make a recommendation one way or the other regarding using these drugs to prevent breast cancer recurrence,” Burstein tells WebMD.
These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.